mep 004a no fault lights working plus more

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Guyfang

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Got a break. At last everyone is gone. I thought about what might have happened. I told you before, the Schmatices don't agree from one sheet to another. But this is what I think happened. The Schmatices show a set of open contacts that were the ground path the we needed to compleat the A9 power circuit. In reality they are closed contacts. They open when K5 is energized. I don't think they opened. Then we had power following that same path, for the fuel pumps. So to be sure, remove the relays from the A5 card, and test them just like you did the K1.

We we were in the SP/relay box before. My first mistake was not having you check out the A5 card for wires, and the second was not having you look at the back of the card. Just to be sure, I will call up Obi Wan again in the morning, on the way to the rally. Won't be able to write what he said til Monday.
 

KLChurch

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I checked the resisters still on the board with a digital ohm meter.
R3 1.498
R8 2.676
R9 5.05
R6 5.05
R7 2.661
I have not found what they should be in the PDF manuals. but plugged the part numbers in google and they are coming up.
However the docs say to check them out off the circuit board.
Will be repairing the bottom of the board and checking the relays.
Kris
 
Last edited:

KLChurch

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By the way I don't think it was your fault. You did in the past tell me to look on the back sides of the circuit boards.
But I believe we were checking the opposite side of the SP box checking the wiring and I believe everything checked OK.
I will never ever check the back side again with a flashlight while still mounted. Don't think I checked A5 for burn marks, but I had to remove A5 in order to check the wires and then I discovered toasted critters.
Kris
 

KLChurch

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I went ahead and reinstalled SP box without addressing R3. Had some good results
Fault indicator lights now working. In the run command low pressure light comes on. Test mode all but the burned out lights come on.
Still two lights are burned out because I have not replaced them.
The pumps still only come on with the battle switch.
Without the pumps running in the run mode I did not try to continue to try to start the engine.
I believe something is still wrong.
Kris
 

KLChurch

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I just checked The IP wires P55X and P80N without the batteries attached and Stop mode.
Put black wire MM on gen a bolt, and other red end separately checked both terminals at IP.
Both showed continuity.
Kris
 
Last edited:

KLChurch

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Decided to check the wires and terminals separately. Still batteries unattached and stop mode
PB0n wire had continuity with frame ground. The terminal with unattached wire no continuity
P55X wire had no continuity and the terminal had continuity.
So I guess that when the wires hitched up both had continuity.
Kris
 

Guyfang

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Location
Burgkunstadt, Germany
View attachment Scan_0001.pdf
I checked the resisters still on the board with a digital ohm meter.
R3 1.498
R8 2.676
R9 5.05
R6 5.05
R7 2.661
I have not found what they should be in the PDF manuals. but plugged the part numbers in google and they are coming up.
However the docs say to check them out off the circuit board.
Will be repairing the bottom of the board and checking the relays.
Kris
The above drawing shows the resisters, and worth. The diagram also shows you what does what. So you can take out the A5 and bench test it. I am going to try and consolidate a few of the posts to save room. The picture of the board repair looked good. The resister that got hot should be changed if you get a chance. To properly check a resister, at least one end needs to be unhooked.
 

Guyfang

Well-known member
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270
83
Location
Burgkunstadt, Germany
I went ahead and reinstalled SP box without addressing R3. Had some good results
Fault indicator lights now working. In the run command low pressure light comes on. Test mode all but the burned out lights come on.
Still two lights are burned out because I have not replaced them.
The pumps still only come on with the battle switch.
Without the pumps running in the run mode I did not try to continue to try to start the engine.
I believe something is still wrong.
Kris
The first thing to do is this.

1. Drain the day tank. Because if the tank is full enough, the pumps will not come on. That's one function of your day tank float. So S2 off, drain the tank and then put the S2 in the run position. What happens? Pumps come on, or not.
 

Guyfang

Well-known member
6,607
270
83
Location
Burgkunstadt, Germany
Decided to check the wires and terminals separately. Still batteries unattached and stop mode
PB0n wire had continuity with frame ground. The terminal with unattached wire no continuity
P55X wire had no continuity and the terminal had continuity.
So I guess that when the wires hitched up both had continuity.
Kris
Your getting good at this!

You can also pull both wire off the L1, (IP solenoid) and do an ohms check there. But normally, if I get ohms between the terminals, I figure its good, as long as I have no continuity between the two terminals and ground.
 

KLChurch

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Ok will drain the tank and go to the run mode then see if the pumps go on.
Does A5 R3 have anything to do with this part of the investigation?
Kris
 

Guyfang

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270
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Location
Burgkunstadt, Germany
Ok will drain the tank and go to the run mode then see if the pumps go on.
Does A5 R3 have anything to do with this part of the investigation?
Kris
Normally I would say no. BUT there must be a set of K7 contacts someplace I cant find on the schematic. The reason R3 is there is to lower amperage to the K7 Coil. The K7 is for Parallel Light operation Sensor. The signal for the K7 is coming from an AC source. So it needs to be changed to DC to drive the relay. But where the set of contacts are, you got me beat if you can find them.
 

KLChurch

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Location
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update
Drained all diesel from the day tank I could . Maybe half gallon.
Attached batteries.
Run mode no pump operation.
Battle mode pump operation.
So far no change with the pumps operations
Kris
 

Guyfang

Well-known member
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Location
Burgkunstadt, Germany
Next step.

Take the J33, (Day tank fuel float) C-plug off.
Put the set in OFF mode.
Take a paper clip and bend it straight.
Insert it in Female pins A&B. Put the set in run mode. The low fuel light should come on.
Put the set in OFF mode, Then remove the paper clip.
Reinsert the paper clip in female pins C&D. Place the set in Run mode. The pumps should run.

Balls in your court!
 

KLChurch

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Location
Montgomery/TX
On the IP.
I took off the wires to the IP while batteries unattached and checked
Checked each terminal to frame ground.
One no continuity and the other had continuity.

Also I did the same thing checking only the wires when they were unattached
They checked opposite of the terminals. One no continuity and the other continuity, opposite from the terminal readings.
Kris
 
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